Rheostat



Nov. 9, 1937.

H.'L. BRADLEY ET AL 2,098,273

RHEOSTAT Filed June 9, 1933 2 Sheets-Sheet 1 IL'IIIIIIIIJ YIIII/IA'IIIIIA llwlllllllllm 'III Nov. 9, 1937- H. BRADLEY ET AL RHEOS TAT Filed June 9, 1933 2 Sheets-Sheet 2 W in Hwy L. Ema/E FEW/H717 Patented Nov. 9 1937 UNITED STATES PATENT OFFICE Barry L. Bradley and Ferdinand J. Haas, Milwaukee, Wit, assignors to Alien-Bradley Comrag, Milwaukee, Wla, a corporation or Wisll.

Application June 9, 1933, Serial No. 675,.

2.01am (cl. 201-55) This invention relates to improvements in Figure 1 is a plan view of a potentiometer emvariable resistance devices and more particularly bodying this invention with its cover removed to rheostats and potentiometer-s ior use with radio and parts thereof broken away and in section to apparatus. show structural details;

The device oi this invention is particularly de- Figure 2 is a transverse section view taken signed to meet an existing and ever increasing through Figure 1 on the plane of the line 2-4; demand for rheostats and potentiometers of Figure 3 is a perspective view illustrating the smaller size and greater efliciency. constituent elements of the potentiometer dis- It is, therefore, a primary object of this inassembled but in their proper order of assembly; vention to provide a variable resistance device Figure 4 is a detail section view taken on the 1 and especially a potentiometer or rheostat which plane of the line 4-4 of Figure 2; is compact and which will operate more efli- Figure 5 is a detail view partly in side elevation cicntly than similar devices now available. and partly in section illustrating an alternate Another object or this invention is to provide manner or mounting the un 011 a pp r in a rheostat or potentiometer so constructed as to D a 15 afford an improved method oi assembly and per- Figures 6 and '7 are perspective detail views mit areduction in the cost of manufacture or showing e cover and base respectively 01 the its parts. modification illustrated in Figure 5.

Another object of this invention is to eiiect Referring w more particularly to the accoma reduction in the number of parts entering into 'Di y drawings in which like numerals di- 20 the construction of a potentiometer or rheostat Cate like parts throughout th s v r v w h by assigning multiple functions t c rtain of th numeral 8 designates the base of the resistance elements. device which in the present instance is illus- Another object oi this invention is to provide trated as a p en m t r- Th se is formed a resistance device so designed nd str t d of suitable insulating material with one face that the entire assembly thereof is accomplished thereof P de t an annular cha l 9 conwithout the use of rivets or screws and in which tr ca y ar a d about a nt al b e II which all the constituent elements are secured in proper ds '0 8 baseassembled relationship merely by the attachment Disposed in the channel 9 1S 8 Segmental flat r the contactor to its actuating stem or shaft. s st s p The s s strip s of a size 30 It is also an object of this invention to provide to be freely though n y e ved in the chana resistance device or the character described helwith One face p which may be quickly and easily attached to a The central portien of the base circumscribed supporting panel with t t use of screws or by the resistor is raised or projected above the 5 nuts. plane of the exposed race 01 the resistor and has A further object of this invention i t provide an annular channel or recess II, the bottom of a resistance device of the character described, Which l c the tWO ends of the resistor Strip wherein the cover for the instrmnentalitles or is increased in pt t the p an f th xp s d the unit has means to hold the device in position surface of the resistor to form w ub a ia ly on a supporting panel. V-shaped notches or recesses I3. These notches 40 With the above and other objectsin view which or recesses ll receive the inner d p t ns ll will appear as the description proceeds, ou i of flat sheet metal terminals l5, which extend vention resides in the novel construction, comradially Over the resistor e P o in direct bination and arrangement of parts substantially contact tihcl'etllith- The depth 0! h r e as hereinafter described and more particularly notches i3 is substantially equal to the thick- 45 defined by the appended claims, it being underness of the terminals so that the outer face of stood that such changes in the precise embodithe terminals is flush with or slightly above ment 0! the hereindisclosed invention may be th ottom of the channe I made as come within the scope of the claims. The outer ends of the terminals pr ject throu h 60 In the accompanying drawings, we have iilusp n n s in an a euflte we l n forming 8 p trated two complete examples of the physical em- .lect c 0f the outer Wall O the chann 9- Th bodiment of our invention constructed according openings II are of sufllcient size to permit the to the best modes we have so far devised for the outer enlarged ends of the terminals to pass Practical application o t prin iples thereoi. therethrough and are so located that when the and in which: terminals are in position, upward or flatwise 55 jection ii to the innermost extremities of therecesses or notches iii, it is evident that when the terminals are in position, they are positively held against lateral motion with respect to the base or the resistor.

Disposed within the central annular channel or recess i2 and overlying the extreme inner ends of the terminal ends it or those portions of the terminal ends embedded in the recesses or notches it, is a washer it of fiber or other suitable insulating material. Also disposed within the central channel it, but outwardly of the insulating washer it is the inner ring shaped end it of a central terminal W. This inner end of the terminal 2i]! snugly fits within the central channel it and its extended outer end, which is stepped downward ly or inwardly as at 2 i passes through an opening 22 similar to the openings it in the arcuate wall projection ill.

The engagement of the intermediate portion of the terminal 2t in the opening 22, together with its snug reception of its inner ring shaped end IS in the central channel l2, firmly holds the central terminal against any possible lateral movement with respect to the base, and by reason of the insulating washer it; it is held out of electrical contact with the inner ends M of the terminals l5.

Diametrically opposite its outer extended end, the inner end 09 of the central terminal has a tongue 23 bent upwardly therefrom for a purpose to be later described.

overlying the inner end portion IQ of the central terminal 20 is a spring washer 24 which is clamped down onto the terminal portion It by a contactor indicated generally by the numeral 25. The contactor 25 is stamped from sheet metal, such as phosphor bronze and has an outer jannular portion 28 and a central hub 21 connected as at 28. The hub 21 has a snap connection 29, to belater described, with the inner end 01' a shaft 30 journalled in the bore ID.

The shaft 30 is shouldered as at 3| to abut the outer end of a boss 32 formed on the base 8 so that inward axial movement of the shaftwith respect to the bore I 0 is precluded. Consequently. when the contactor is connected to the inner end of the shaft by means of the connection 29, the terminals and also the resistor strip will be firmly held down in the channels or recesses in which they are received, the spring washer 24 providing a spring tension to insure a. firm as sembly.

The snap connection 29 comprises a groove 33 in the outer end of the shaft and a square hole' 34 in the hub of the contactor. The extreme end of the shaft outwardly of the groove 33 has two opposite sides flattened to the bottom of the groove 33, as at 35. Two opposite sides 36 of the a are bent outwardly so that when the sides 36 are engaged in the groove the outstruck sides 31? engage the fiat faces 35 of the shaft. In

this manner, the contactor is secured on the shaft against rotation.

At a point opposite the connection 28 between the hub and annular portion 245 of the contactor, the annular portion has a tit tit formed thereon to project toward the resistor. Engaged'with the tit it is a button 39 arranged for sliding engagement with the exposed face of the resistor to traverse the same upon rotation of the contactor.

To provide contact pressure, the annular portion of the contactor is sprung inwardly with respect to its hub.

Rotati of the contactor is limited by the engagerne t of stop abutments til formed on the contactor adjacent the connecting portion 28, with the tongue 23, which projects upwardly through the annular space between the hub and outer portion of the contactor, in the path of the stop abutments til.

It is to be noted that the tongue 23 is nested in a notch 23' in the base and is thereby mechanically strengthened to permit its being bent by forced engagement of the stop abutments 40 therewith. I

The resistor and its associated elements are closed by a cover or cap 4! disposed over the outer face of the by means of snap fastenings 42. The edge of the cover engagesan annular shoulder 43 en-- circling the base, and to accommodate the arcuate wall H, the cover is suitably cut away.

The attachment of the potentiometer to a sup- 5 snap into depressions 49 in the walls of thenotches 41 to hold the clip in position. This manner of moun ing the potentiometer from the supporting panel does away with clamping nuts and screws and aflords a secure mounting in an exceedingly simple manner.

To secure the unit axis of its mounting, ject from the edge of the cover to enter apertures formed inthe panel.

Amodified manner of mounting the unit on the supporting panel is illustrated in Figures 5, 6, and 7. In this construction, the clip 46 is omitted and tangs 5| similar to the tangs 53 serve to mount the unit. For this purpose, the tangs 5|, which also provide the means for securing against rotation about the the cover on the base, are merely struck over the face of the panel as clearly shown in Figure 5. To secure the cover'on the base, theinner portions of the tangs 5| are crimped as at 52 to snap into notches 53 in the base.

From the foregoing description takenin connection with the accompanying drawings, it will be readily apparent to those skilled in the art base and attached to the base The clip 46 is a U-shaped spring one or more tangs 50 prothat this invention affords a; substantial improvement in the construction of rheostats and potentiometers, and that the novel manner of assembling its various parts permits not only a. very but also-provides a more compact construction,

emcient and less expensive unit than has heretofore been possible.

What we claim as our invention is: l. A rheostat, comprising a base, a resistor embedded in the base with one surface exposed, a terminal for the resistor partially embedded in the base and having a part overlying and conin a position bearing down on said embedded portion of the terminals whereby the contactor secures the resistor and both terminals assembled with the base.

2. A rheostat comprising a base of insulating material having a central bore and provided with an annular channel concentric with the bore and a terminal receiving recess, a resistor disposed within said channel with one surface thereof exposed, a resistor terminal having a portion thereof received in said recess and overlying and contacting the exposed surface of the resistor, a shaft rotatable in the bore, a contactor to traverse the exposed surface of the resistor, a contactor terminal electrically connected with said contactor and having an interfitting engagement with the base so as to be held against lateral displacement, the contactor having a part overlying the terminals but insulated from the first mentioned resistor terminal, and means to attach the contactor to the shaft in a position with its said part bearing down on the terminals at all times so that the contactor holds the first mentioned terminal down on the resistor and secures the resistor in the channel and the first mentioned terminal in its recess and in electrical contact with theresistor and maintains the interfltting engagement between the contactor terminal and the base.

3. In a rheostat, a base of insulating material having a channeled and recessed surface, a resistor disposed in said channel with one surface exposed, a terminal for the resistor partially received in the recess and having a part overlying and contacting the resistor, a contactor to traverse the exposed surface of the resistor, and means to mount said contactor with a portion thereof overlying and bearing down on said terminal at all times but insulated therefrom so that thglcontactor' alone upon being mounted secures t e resistor and terminal in position. a

4. In a rheostat, a base having a circular channel and a radial recess opening to the inner edge of the channel, the channel being deeper than the recess, a resistor disposed within the channel with a surface thereof exposed and substantially flush with the bottom of the recess, a terminal having a part snugly received in said recess and extending out. over the exposed surface of the resistor in electrical contact therewith, and means disposed over the terminal part which is seated in said recess to bear down on the terminal and hold the terminal and the resistor assembled'with the base.

5. A variable resistance device comprising a base, a resistor disposed in an open recess in the base, a terminal for the resistor having a part received in an open recess in the base and a part overlying and directly engaging the resistor to have electrical contact therewith, a contactor terminal having a part disposed in another open recess in the base and bearing down on the first mentioned terminal but electrically insulated therefrom, a contactor mounted to traverse the resistor, and pressure means confined between the contactor and said contactor terminal, whereby mounting of the contactor firmly holds the resistor and terminals down in their respective recesses.

6. A variable resistance device comprising a base of insulating material having a central bore, an annular channel concentric to the axis of said bore and opening to one face of the base and recesses also opening to said side of the base, a

resistor segment disposed within said channel with one surface exposed, a terminal having a part received in one of said recesses of the base and having another part directly overlying the exposed surface of the resistor, a contactor terminal having a part disposed in another recess of the base and bearing down on the first mentioned terminal but. electrically insulated therefrom, a contactor, a shaft journalled in said bore-and held against axial movement toward the face of the base on which the resistor and terminals are assembled, and a connection between the contactor and the shaft whereby the contactor is movable by rotation of the shaft to traverse the resistor and whereby the attachment of the contactor to the shaft secures the resistor and terminals in position.

7. A variable resistance device comprising a base of insulating material having a bore therethrough. a resistor, a contactor to traverse the resistor, a terminal having a part overlying the resistor in electrical contact therewith, the base being formed to hold the terminal and the resistor against lateral shifting, an operating shaft rotatable in said bore, and a connection between the shaft and the contactor, the contactor being disposed outwardly of the resistor and said terminal and having a part bearing down on the terminal at all times to hold the terminal and the resistor in electrical contact and secure them on the base whereby the contactor upon effecting said connection between the contactor and shaft secures all elements of the device assembled with the base.

8. In a rheostat, a base having a circular channel and a radial recess opening to the inner edge of the channel, a resistor disposed in the channel with a surface thereof exposed, a terminal having a partseated in said recess and extending out over the exposed surface of the resistor in electrical contact therewith, and means disposed over the terminal part which is seated in said recess but insulated therefrom to bear down on the terminal and hold the terminal and resistor in good electrical contact with each other and properly assembled with the base.

9. In a rheostat, a base having a circular channel and a radial recess opening to the inner edge of the channel and radially in line with an opening through the outer wall of the channel, a resistor disposed within the channel with a surface thereof exposed, a terminal having an inner end portion snugly fitted in saidrecess and an outer end portion projecting out through the opening .in the outer wal of the chan el with its medial portion positioned over and in electrical contact with the exposed surface of the resistor, and means disposed over the terminal part seated in the recess to bear down on the terminal and hold the terminal and resistor in good electrical contact and properly assembled with the base.

19. In a rheostat, a base having a central bore and having a circular channel concentric to the bore and a radial recess opening to the inner edge of the channel and radially in line with an opening through the outer wall of the channel, a resistor snugly fitted in the chael and held against lateral or rotational movements therein, a shaft rotatable in the bore, a terminal having an inner end portion seated in said recess and an outer end portion projecting through the operung in the outer wall of the channel with its medial I portion disposed over and in electrical contmt with the resistor, and means mounted on said shaft and bearing down on the terminal to hold the terminal and the resistor in firm electrical contact'with each other and properly assembled with the base.

ii. In a rheostat, a base of insulating material having a circular channel and a radial recess opening to the inner edge of the channel and having a plurality of radial openings in the outer wall of the channel, a resistor disposed in'the channel, a resistor terminal having an inner end portion seated in said recess and an outer portion projecting out through one of said openings with its medial portion positioned over and in electrical contact with the resistor, a contactor mrminal having an outer end portion projecting through another of said radial openings and an inner apertured portion disposed over the resistor terminal but insu ated therefrom, the base being formed to have interfitting engagement with said inner apertured portion of the contactor terminal, an operating shaft journalled in the base, and means for securing the contactor to the shaft with a portion thereof pressing down on its terminal to hold it and the resistor and resistor terminal in proper assembled relationship on the base.

12. In a variable resistance device, a rotatable operating shaft having a shoulder intermediate its ends, a movable contactor, a readily detachable non-rotatable connection between the contactor and one end portion of the shaft, a base of insulating material bored to rotatably receive said end portion of the shaft and engaging the shoulder thereon so that said base is disposed between the shoulder on theshaft and the movable contactor, a resistor overlying that side of the base which faces the contactor, said resistor being a self supporting composition unit independent of the base and readily separable therefrom and having one surface exposed for engagement therewith by the movable contactor, a metal ter minal for the resistor entirely separate from the resistor and overlying the exposed surface thereof. and resilient means confined between the con-- iactor and said terminal to press the terminal against the resistor and the resistor against the base, and said base having a surface formation to hold the resistor and terminal against lateral shifting.

13. A variable resistance device comprising a base of insulating materialhaving an inner face and an outer 'face and provided with a bore, a shaft having an outer end portion adapted to receive' an actuating knob and ah inner end portion rotatable in the bore with its extremity projecting from the end of the bore at the inner face of the base, means to limit inward longitudinal movement of the shaft, a substantially annular resistor overlying the inner face of the base and having an interfitting engagement with the base whereby said resistor is held against lateral shifting with respect to the base, terminal for the resistor entirely separate therefrom with it portion thereof overlying part of the resistor to confine the resistor between it and the inner face of the base, said terminal having an interfitting dfilbdfiid engagement with the base whereby the terminal is held against lateral displacement with respect to the base and the resistor, and means attached to the inner end portion of the shaft and bearing down on the terminal to hold the terminal in engagement with the resistor and to hold the tergiinal and resistor against the inner face of the ase.

it. A variable resistance device comprising a base of insulating material having a'central bore and provided with an annular channel con centric to the bore and a radial recess opening to the innee of the channel and having radial openings 3; i ough the outer wall of the chane nel, one of which is radially in linewlth said recess, a resistor seated in said channel and held against lateral and rotational movements therein, a terminal having an inner end portion seated in said'recess and an outer end portion projecting out through the aligned opening in the outer wall of the channel with its medial portion positioned over. and in electrical contact with the exposed surface of the resistor, a conta'ctor terminal having an inner apertured end portion disposed coaxially with the bore and an outer end portion extending through another of said radial openings in the outer wall of the channel, the base being formed to have an interfltting engagement with the apertured inner end portion of said contactor, an insulating barrier between the terminals, a contactor to traverse the exposed surface of the resistor, and an operating shaft journalled in the base and to which said contactor is attached, said contactor' overlying the contactor terminal and pressing down on the contactor terminal to aflord good electrical connection between it and said contactor terminal and to hold said resistor and its terminal in good electrical contact and properly assembled with the base. 1

15. in a rheostat, a base of insulating material, a composition resistor readily removably em,- bedded in the base, a metal terminal readily removably embedded in the base, with a portion thereof overlying the resistor in electrical contact therewith, a shaft journalled in the base, and means carried by the shaft and pressing down on the terminal to hold the same in electrical engagement with the resistor and to maintain the resistor and terminal base.

16. In a rheostat, a base of insulating material having'a bore therethrough, a ringlil:e resistor readily removably embedded in the base with one surface exposed, a terminal for the resistor likewise readily removably embedded in the base, a part overlying the exposed surface of the resister in electrical contact therewith and extending radially therebeyond, a shaft journalled in the bore, meanacarried by said shaft to at all times press down onto the terminal terminal in good electrical contact with the resistor and maintain the terminal and resistor properly embedded in the to hold the,

ill

embedded in the base, and a contactor movable with the shaft to traverse the resistor.

l7.- In a rheostat, a. base of insulating material, a flat ring-like resistor\with one side in flat engagement with the baseand its other side ex-. v posed, a sheet metal terminal extending radially out over the exposed side of the resistor in electrical contact therewith, the base being formed to engage the resistolr and terminal so as to secure these parts against lateral movement with respect to the base, a shaft journalled in the base coaxialiy with the ring-like resistor, an insulating member overlying the terminal, a contactor mounted on the shaft and arranged to traverse the resistor, and yieldable means between the contactor and said insulating member to press the insulating member down onto the terminal at all times and thereby hold the terminal in good electrical contact with the resistor and secure these parts to the base.

18. Ina manual control device for radio apparatus and the like adapted to be mounted on one side of a supporting panel, a base of insulating material, a boss formed integrally with and projecting from one face of the base for reception in an aperture in the panel, there being a bore through the base and boss, instrumentalities mounted on the opposite face of the base, an operating shaft for the instrumentalities journalled in said bore with one end projecting from the boss to be disposed at the side of the panel opposite that at which the device is mounted, a cup-shaped sheet metal cover telescoped over the base so as to enclose the instrumentalities thereon, and common means on the side wall of the cup-shaped cover to coact with a shoulder on the base for releasably holding the cover in position and for coacting with the boss in mounting the device on the panel.

19. In a manual'control device for radio apparatus and the like adapted to be mounted on one side of a supporting panel, a base of insulating material, a boss formed integrally with and propecting from one face of the base for reception in an aperture in the panel, there being a bore through the base and boss, instrumentalities mounted on the opposite face of the base, an operating shaft for the instrumentalities journalled in said bore with one end projecting from the boss to be disposed at the side of the panel opposite that at which the device is mounted, a cup-shaped sheet metal cover telescoped over the base so as to enclose the instrumentalities thereon, a plurality of tangs projecting from the peripheral edge of the cover side wall to extend beyond the base for reception in openings in the supporting panel other than the aperture in which the boss is received so as to coact with the boss in mounting the device on the supporting panel, and means on said tangs having a detent connection with the base for releasably holding the cover thereon.

20. In a manual control device for radio apparatus and the like adapted to be mounted on a supporting panel, a base, instrumentalities mounted on the base, an actuating shaft journalled in and supported entirely by the base for actuating said instrumentalities, a cup-shaped metal cover disposed over said instrumentalities with its side wall telescoped over the base, a tongue integral with and extended from the edge of the cover side wall beyond the base for engagement in an aperture in the supporting panel to position the device thereon, and a detent on the tongue engaging the base to hold the cover on the base, said detent being retained in proper engagement with the base by inherent spring ten- 7 sion of the tongue.

HARRY L. BRADLEY. FERDINAND J. HAAS. 

